Zemach moments of ${}^3\mathrm{He}$ and ${}^4\mathrm{He}$

The world data on elastic electron scattering on ${}^3\mathrm{He}$ and ${}^4\mathrm{He}$ is used to determine the Zemach moments ${\langle r\rangle }_{\left(2\right)}$ and ${\langle r^3\rangle }_{\left(2\right)}$. These quantities are required to interpret the Lamb shift and hyperfine splitting data of muonic helium presently being measured at the Paul Scherrer Institute by the CREMA Collaboration. The rms radii are determined as well.

Figure 1

Convergence of the integral for ${\langle r^3\rangle }_{\left(2\right)}$.

Figure 2

Ratio of experiment to fit for ${}^3\mathrm{He}$. Data with $\delta \sigma /\sigma >0.1$ are not shown.